You know how when you shop on Amazon there is a price and a then a "list price" which is usually much higher?

The effect is that you feel like you're getting a big discount shopping on Amazon.

It turns out Amazon might be publishing list prices that are too high.

Mouse Print first noticed the problem with an array of general consumer products such as Kraft's Mac & Cheese and a 100-count box of Splenda.

As if this afternoon, most of these prices have been fixed, except for a ton of pet food items.

Take for example the dog treats you see above. The retail value of one Merrick Flossies is approximately $4, making a 50-count supply valued at no more than $200. Yet Amazon claims the list price stands at a whopping $422.89, more than doubled what it should cost.

We tried to contact Amazon for comments, but did not receive a response.

The incident reminds us of last year when Amazon listed a seemingly normal book about flies for $23,698,655.93. Biologist Michael Eisen blogged about the unrealistic selling price, and documented how Amazon's price for the book The Making of a Fly constantly went up day after another.

Here's what happened: A professor required this book for a class and students naturally flocked to Amazon to purchase the text. Eventually, only two sellers still had the product available.

Because the book quickly became an exclusive, hot ticket item, Amazon's algorithm for retailers to competitively price their product catapulted the retail value to more than $23 million.

We're not sure if this is the same situation with the pet food offerings on the site, but it seems hard to believe the world is running out of doggie treats.

Disclosure: Jeff Bezos is an investor in Business Insider through his personal investment company Bezos Expeditions.